1. Field of the Invention
The present invention relates to a method of removing hair and hair removal device that make use of a combination of two physical principles by applying radio frequency (RF) field and ultrasound vibrations to hair and their follicles.
2. Description of the Related Art
Recent hair removal or epilator devices currently in use are tweezers type units through which radio frequency (RF) energy is applied to the hair shaft. Typical of such devices and methods for removal of hair are described in U.S. Pat. Nos. 4,174,713; 4,566,454; and 5,049,148; each of which is hereby incorporated by reference as if fully set forth herein. The methods taught in the above-mentioned patents require in many instances thirty seconds treatment of each hair to be removed. Sufficient time was required in order to effectively damage the follicles (root system) of the hair. In such a way, the hair may be removed by a very gentle upward lift rather than by the sharp tug, which would be normally applied for the removal of a single hair by a tweezers without any treatment of the hair. Specifically, U.S. Pat. No. 4,566,454 discloses utilizing the resonant frequency of hair in conjunction with RF.
More recently, an even faster hair removal system, which, by use of RF energy, yielded damage to the root in less than half the time required by earlier methods, is disclosed in U.S. Pat. No. 5,364,394, which is incorporated herein by reference. There are likewise known U.S. Pat. Nos. 5,226,907 and 5,425,728, which disclose using the wave energy of a laser in conjunction with hair removal by the application of a contaminant oil on the skin.
A system for permanent removal of multiple hairs disclosed in the U.S. Pat. No. 5,470,332 includes an adhesive layer, a structural layer disposed adjacent the adhesive layer, and a conductive material. The conductive material functions to provide power from a power source to hairs to be treated that extend up through the adhesive layer and contact the conductive material. A method of removing multiple hairs and inhibiting future hair growth includes the steps of applying a conductive solution to the skin, pressing on an adhesive layer, applying power for a period of time sufficient to destroy the matrix area of the hair, and allowing the treated hair to either be removed immediately or to stay in the skin for a period of time sufficient for the chemical reaction induced at the matrix area to continue long enough to destroy the matrix area and prevent regrowth of the hair. The preferred sources of power include DC power, radio frequency power, galvanic thermolysis, and combinations thereof, such as DC-biased RF or blend.
Method of removing hair from the body and inhibiting future growth disclosed in U.S. Pat. No. 5,846,252 provides for the removal through the use of electromagnetic (e.g., AC, DC, blend, and laser) energy by treatment of the hair prior to the application of such electromagnetic energy to reduce the electromagnetic energy resistance of the hair. Such hair treatment may include applying conductive solutions, pre-treating the hair to yield an alkaline environment (i.e., hair is made more alkaline), and adding graphite, metal, conductive non-metal solids, viscous materials, and liquids.
Also known in the art is a Japanese patent application No. 02-279107 published on Nov. 15, 1990, and describing a method and device for ultrasonic depilation. The device contains an oscillation circuit supplying ultrasonic vibrations to a vibrator that is provided with a pick adapter ending with a pair of pick pieces. When a hair is held by the pick pieces, the ultrasonic vibration is transferred to the hair. In such a way, while allowing the ultrasonic vibration to work on the root of the hair to draw it out, the hair is drawn out gradually by its peak. When tensile force, for instance, of 50 to 100 g per piece is allowed to work, the bonding strength between the root and the skin weakens, xe2x80x9cand the depilation can be executed smoothly without allowing a man to feel a pain so much.xe2x80x9d
WO 93/04636 describes a method based on the observation that by mixing a conductive gel with a treating product, for example a lotion for producing atrophy of the hair roots, it was possible by high-frequency transcutaneous induction to cause the treating product to penetrate into the hair follicles and hence carry out a treatment. The method hence enables a treatment of the skin to be carried out, notably a cosmetic treatment, for example to achieve long lasting depilation. It allows a punctual and effective application down to the follicles without a delicate manual intervention. To carry out the method, WO 93/04636 also describes an apparatus comprising a handleable member, for contacting the skin, having a non-conductive body provided with a contact surface adapted to be applied to the skin. This surface comprises a plurality of discrete conductive electromagnetic emission points, for example formed by exposed parts of turns of a solenoid embedded in the body of the contact member. These points are accessible through openings in this surface and are preferably set back with respect to the latter, so that during use of the apparatus, these points may contact conductive gel applied to the skin. These discrete emission points emit a high-frequency flux of electromagnetic energy, advantageously a pure emissive current, supplied by a high-frequency oscillatory power circuit. The handleable member of the above-described apparatus thus forms a focused probe, whose high-frequency energy produces a point-wise action through the loaded gel. By arranging the discrete emission points in a suitable manner on the contact surface, a simultaneous action is obtained on all of the follicles of an area of the skin. For example, the discrete emission points are aligned in one or several rows along an oblong contact surface, whose dimensions are adapted to the part of the body to be treated. Preferably, several interchangeable rigid contact members are provided having contact surfaces of different shapes and/or of different sizes, and possibly also an interchangeable needle fixture, thus enabling treatments suitable for all types of pilosity. The high-frequency electric generator circuit of the apparatus advantageously comprises a high-frequency oscillatory power circuit comprising a transistor connected as a power oscillator in combination with a pair of square-wound self-inductance coils, and an electrode. Thus, the impedance of a treated person""s body may be added to that of the self-inductance coils to increase the frequency of the emissive current during use.
The above-described devices lack efficiency as far as quality of removing hair, painlessness of the depilation, and preventing hair regrowth are concerned.
It is therefore a principal object of the present invention to provide a method for removing hair that, while preserving main advantages of the methods known in the art, would be free of their drawbacks. Another object of the invention is to provide a hair-removing device that could combine high efficiency in action with painlessness and convenience for a user.
The above objective is met in the invention by virtue of a method that comprises in conjunction the steps of applying radio frequency radiation to a selected skin zone, from which hair is to be removed, whereby hair follicles are destroyed, applying ultrasound waves to the skin zone to shake up the hair with the destroyed follicle and thus slacken the union between the hair and the skin zone and underlying area, and pulling the slackened hair out.
The exposure of hair to ultrasound can be supplemented by the action of sonic waves to further add to the effectiveness of the method.
To enhance effectiveness of the method, frequency of sonic waves applied to the skin can sweep. The coincidence of the frequency of the applied sonic waves with a natural frequency of a hair will cause a resonance that will enhance the slackening effect of the sonic waves.
A device for removing hair from body skin according to the method comprises means for electromagnetically destroying hair follicles at a selected skin zone, means for applying mechanical ultrasound waves to the zone for shaking up the hair with the follicles destroyed by the destroying means, to thereby slacken the union between the hair and the skin zone and underlying area, and means for pulling the slackened hair out.
Preferably, the means for destroying hair follicles includes a radio frequency generator, the means for applying ultrasound waves for shaking up the hair with the follicles includes an oscillator, and the means for pulling the slackened hair out includes tweezers.
The device may further advantageously comprise a radio frequency power selector controlling the radio frequency generator. Thus, the intensity of radio frequency radiation can be varied depending on the texture of hair and sensitivity of the selected skin zone.
The device may also comprise means for creating sonic waves, separate from the oscillator or made integral therewith.
The device further comprises a piezoelement generating the mechanical waves, which is controlled by the oscillator. Upon using ultrasound waves only, the oscillator preferably produces an output signal in the range between about 60 kHz and about 300 kHz, whereas the radio frequency generator operating frequency is preferably 27.125 MHz.